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Method of manufacturing glass substrate for magnetic disk, method of manufacturing magnetic disk, and polishing apparatus of glass substrate for magnetic disk

a technology of glass substrate and magnetic disk, which is applied in the direction of base layer manufacturing, edge grinding machines, manufacturing tools, etc., can solve the problems of inconvenient formation of portions, thermal asperity trouble, read error, etc., and achieve high processing accuracy, high polishing speed, and low inner diameter tolerance

Active Publication Date: 2009-09-17
HOYA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a method of manufacturing a glass substrate for a magnetic disk, which involves polishing the inner circumferential end face of the glass substrate. The technical effects of this invention include improved smoothness and flatness of the magnetic disk surface, reduced flying height of the magnetic head, and improved accuracy control of the inner diameter of the inner circumferential end face of the magnetic disk. Additionally, the invention addresses the issue of thermal asperity trouble caused by small convex or concave portions on the magnetic disk surface.

Problems solved by technology

A magnetic head mounted with such a magnetoresistive effect element sometimes induces a thermal asperity trouble as a unique trouble of the head.
The thermal asperity trouble is a trouble where when a magnetic head in flying in the air passes above a small convex or concave portion on a magnetic disk surface, the magnetoresistive effect element is heated due to adiabatic compression of air or contact with the small portion, causing a read error.
Moreover, when a magnetic layer is formed on a glass substrate with dust or a foreign substance being adhered, a convex portion is inconveniently formed, therefore the glass substrate is required to be highly cleaned for completely removing the dust or the foreign substance.
Moreover, a large dimension error in inner diameter leads to a possibility of inducing a mechanical error in stacking servo (writing of servo information into a magnetic disk) performed before the magnetic disk is assembled in a magnetic disk device such as HDD, or a possibility of inducing bad fitting of the disk with a spindle in disk stacking.
The inner circumferential end face of a magnetic disk is small in surface area compared with a main surface, and when a rotational center of the magnetic disk is displaced due to the dimension error in inner diameter, it is difficult to dispose a head of HDD in a correct position on the HDD, consequently data are hardly recorded or reproduced.
In the case that the dimension error in inner diameter of a magnetic disk is large, when the magnetic disk is assembled in HDD, alignment between a servo pattern and a position of a recording / reproducing head of HDD being a product is disordered, therefore recording / reproducing of data is still not normally performed.
While a technique of adjusting alignment for correcting such a positional relationship is disclosed, the technique does not give a drastic solution for suppressing the dimension error in inner diameter.

Method used

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  • Method of manufacturing glass substrate for magnetic disk, method of manufacturing magnetic disk, and polishing apparatus of glass substrate for magnetic disk
  • Method of manufacturing glass substrate for magnetic disk, method of manufacturing magnetic disk, and polishing apparatus of glass substrate for magnetic disk
  • Method of manufacturing glass substrate for magnetic disk, method of manufacturing magnetic disk, and polishing apparatus of glass substrate for magnetic disk

Examples

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example 1

[0116]In the example, a glass substrate for a magnetic disk and a magnetic disk were manufactured through the following steps. Particularly, in an end face polishing step, the polishing method according to the embodiment is used.

(1) Shaping Step and First Lapping Step

[0117]First, melted alminosilicate glass was molded into a disk shape by direct press using an upper mold, a lower mold, and a sleeve mold, so that amorphous plate-like glass was obtained. As the alminosilicate glass, glass for chemical strengthening was used. In addition to direct press, the disk-like glass substrate for a magnetic disk may be obtained by cutting sheet glass, which is formed by a down draw method or float method, by a grinding stone. As the alminosilicate glass, chemical strengthening glass was used, which mainly contains SiO2 of 58 to 75 wt %, Al2O3 of 5 to 23 wt %, Li2O of 3 to 10 wt %, and Na2O of 4 to 13 wt %.

[0118]Next, both main surfaces of the plate-like glass were subjected to lapping to be for...

example 2

[0152]A glass substrate for a magnetic disk was manufactured in the same way as in the example 1 except for performing a chemical strengthening step before an end face polishing step in the descried manufacturing method. Removal depth of the inner circumferential end face in the end face polishing step was 4 μm, and inner diameter circularity of the glass substrate was 3 μm after the end face polishing step. A magnetic disk was manufactured in the same way as in the example by using the glass substrate for a magnetic disk. The magnetic disk was subjected to a glide test, as a result, hit or crush was not found. Furthermore, a reproducing test was performed using a magnetoresistive head, as a result, false operation caused by thermal asperity was not found in reproducing.

[0153]While the preferred embodiment of the invention was described with reference to accompanying drawings hereinbefore, it will be appreciated that the invention was not limited to such embodiment. It is obvious th...

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Abstract

A method of manufacturing a glass substrate for a magnetic disk is provided, by which polishing accuracy on an inner circumferential end face of a glass substrate is improved, and a thermal asperity trouble can be avoided.In a method of manufacturing a glass substrate for a magnetic disk, by which an inner circumferential end face of a cylindrical polishing object 12 is polished, the polishing object including a plurality of glass substrates 20 stacked on one another, a plurality of polishing cloths disposed around a rotation axis of an inner circumference polishing section having the rotation axis are contacted to the inner circumferential end face 116 of the polishing object at even pressure, then a polishing liquid is supplied between the inner circumferential end face of the polishing object and the inner circumference polishing section, and then the inner circumference polishing section and the polishing object are relatively rotated / moved with the rotation axis as a center, or relatively moved in a direction of the rotation axis, thereby the inner circumferential end face of the polishing object is polished.

Description

TECHNICAL FIELD[0001]The present invention relates to a method of manufacturing a glass substrate for a magnetic disk, by which an inner circumferential end face of a glass substrate is polished, a method of manufacturing a magnetic disk, and a polishing apparatus of the glass substrate for a magnetic disk.BACKGROUND ART[0002]Recently, with sophistication of informatization technology, information recording technology, particularly magnetic recording technology is significantly improved. As a substrate for a magnetic recording medium such as HDD (Hard Disk Drive) as one of media for such magnetic recording, an aluminum substrate has been widely used. However, with reduction in size or thickness of a magnetic disk, and with increase in recording density, demand for a glass substrate is now increased, the glass substrate being high in surface flatness and high in strength compared with the aluminum substrate.[0003]Moreover, with increase in recording density in magnetic recording tech...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B24B9/08B24B7/24B24B1/00
CPCG11B5/8404C03C19/00
Inventor UEDA, MASAAKI
Owner HOYA CORP
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